The 45-year-old, who currently leads the Asian Tour's Order of Merit, sank four birdies against a lone bogey for a three-under-par 69 at the Amata Spring Country Club as his round was matched by South Africa's Jbe Kruger, who is third on the Merit rankings.
Fourth ranked Gaganjeet Bhullar of India carded a 71 in what is the penultimate event of the 2012 Asian Tour season. Australia's Marcus Fraser, second on the Order of Merit, is not playing this week.
The unorthodox-swinging Thaworn produced a chip-in birdie from 40 yards at the seventh hole and took full advantage of his straight hitting game to give himself three other birdies on the first, third and 11 holes.
"I have very good tee shots and missed only one fairway which I made par. My tee shot was good, chipping was also good," said Thaworn, who has won three times this season and holds the most win on Tour with 15 titles.
"I'm very happy with my score especially on this golf course. This is not an easy course. It is very tough for me but it is easier for the long hitters. It was nice to sink some putts," added the Thai, who outscored playing partner and defending champion Lee Westwood by one shot.
The slightly-built Kruger, who is some US$217,000 behind Thaworn in the race to become Asia's number one, was delighted he stayed bogey-free in a round which included birdies on the sixth, seventh and 17th holes.
"I'm playing better. Hitting it a lot straighter but just couldn't get the putter going. The winds were probably a club and a half more in the afternoon but the greens tend to stand up more in the afternoon. I just couldn't get the putter going," said Kruger, winner of the Avantha Masters in India earlier in the season.
"No bogeys, that's good. The rough is penal here. I was in there once and I managed to get it up and down from 100 yards which was good. I'm not really going to watch Thaworn. It doesn't matter what he is doing. You need to take the pressure off yourself. If I can keep on hitting it good, you never know if the putts go in," he added.